[MEncoder-users] new doom9 codec comparission

Rich Felker dalias at aerifal.cx
Fri Dec 2 20:33:30 CET 2005

On Fri, Dec 02, 2005 at 09:56:25AM -0800, Corey Hickey wrote:
> Michael Niedermayer wrote:
> >>>I can only conjecture as to why they are different and which one is
> >>>correct; the only thing I am pretty sure about is that
> >>>mplayer/mencoder decodes the DVD that way -- it doesn't get altered
> >>>during the encoding process.
> >>
> >>The doom9 shot has clearly been cropped, sized and aspected so why
> >>not gammaed too? I'd guess it's a screenshot so it's been
> >>postprocessed by whatever is playing it.
> >>
> >>Interestingly, when I play your clip in mplayer (vo x11 without
> >>postpro) it does not appear quite as dark as your frame does. It
> >>could be an optical illusion due to the movement though.
> > 
> > 
> > an additonal source of brightness change is that jpeg and mpeg use
> > different ranges for the luma component, and IIRC mplayer&mencoder 
> > ignore this, probably most other tools too, i think ffmpeg doesnt.
> > also keep in mind that xv & x11 tend to look different on many
> > grafic cards
> For me, xv, x11, png, and jpeg all looked the same.
> Doom9 told me that it was probably due to the windows programs
> displaying the video more brightly, and, as long as the encoded video
> has the same brightness as the original, I shouldn't worry about it.

It's due to -vo jpeg generating invalid jpeg (assuming jpeg yuv scale
is same as mpeg yuv scale, which it's not).


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